Modern flight control systems are required by Federal Air Regulations to provide safe and reliable control of an aircraft. Any failure condition that prevents continued safe flight and landing must be extremely improbable. In the past, flight control systems were implemented using discrete analog components. The use of such analog components enabled system designers to develop flight control systems that could be fully tested and analyzed in order to certify their conformance with the safety requirements of the Federal Air Regulations relatively quickly and inexpensively.
More recently, flight control systems have been developed using digital components, such as arithmetic logic units (ALUs) and other digital processing units. These digital flight control systems provide increased performance and take up less space and weight on the aircraft. However, it has generally been found that the hardware and software of these systems is of such complexity that they cannot be fully tested and analyzed without significant expense and difficulty. In addition, it is not feasible to use commercially available digital components within a flight control system because they are not generally tested and analyzed at the level required by the Federal Air Regulations. Further, the structural implementation of commercially available digital components may not be known and, consequently, there is no way to validate their conformance with the safety requirements of the Federal Air Regulations.
Accordingly, it is desirable to provide an ALU for use within flight control system that is fully testable and analyzable. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.